JPH0823110B2 - Tarpaulin that can be heat-sealed - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealable waterproof sheet, and more particularly to a heat-sealable waterproof sheet having excellent stain resistance and weather resistance.

[0002]

2. Description of the Related Art Conventionally, for example, a flexible sheet having a soft vinyl chloride (PVC) resin layer on one or both sides of a fibrous base fabric has been used for a large tent such as an air dome.
Such a sheet has advantages peculiar to PVC in terms of processability, economical efficiency, flameproofness, etc. On the other hand, since such a tent is exposed to the outdoors for a long time,
Even if the stabilizers to be blended are thoroughly examined, the resin gradually decomposes over the years, and the plasticizer migrates to the surface to gradually make the surface sticky and dust on the surface. It had a serious defect such as adherence and contamination.

As a countermeasure against this, an acrylic resin film layer is formed on the upper surface of the PVC layer to cover the drawbacks of the conventional laminated product having only the PVC layer and obtain a predetermined effect. However, depending on the condition of use of the laminated product, cracking may occur in the acrylic resin film layer under conditions such as strong rubbing, resulting in a marked reduction in the useful life of the laminated product. Has not yet reached.

Therefore, the surface of such a laminated sheet is
Attempts have been made to improve the weather resistance and stain resistance by forming a film made of vinylidene fluoride resin / acrylic resin / PVC resin by adhering it and using the vinylidene fluoride resin layer as the outer surface. However, when such a waterproof sheet is sewn with a sewing machine and used, there is a problem that water leaks from the seams. Further, since the sewing machine sewing has a poor work efficiency, a high-frequency or hot air is often used instead to perform the heat-sealing, but the laminated sheet having the vinylidene fluoride resin layer as the outer surface is heat-sealed. There is a problem that the vinylidene fluoride resin layer does not adhere even if it is attempted to be joined by sewing. Therefore, further improvement of this sheet has been desired.

[0005]

The present invention not only has excellent antifouling properties and weather resistance, but is also capable of being heat-sealed and has a highly durable antifouling property. It is intended to provide a useful waterproof sheet.

[0006]

According to the present invention, there is provided a waterproof sheet which can be sewn by heat fusion and which is excellent in stain resistance and weather resistance. The heat-sealable waterproof sheet of the present invention has a waterproof sheet substrate having a fibrous base cloth and a waterproof layer formed on the surface or both front and back surfaces thereof and made of natural rubber, synthetic rubber or synthetic resin. A vinylidene fluoride resin layer is formed as the outermost layer on the upper surface side of the base body, and an upper surface acrylic resin layer is continuously formed under the outermost layer, and the vinylidene fluoride resin layer is formed on the lower surface side of the base body. A lower surface acrylic resin layer is formed as the outermost layer. In the waterproof sheet of the present invention, when the vinylidene fluoride resin layer as the outermost upper surface and the lower surface acrylic resin layer as the outermost lower surface are superposed, they can be firmly joined by heat fusion and sewn.

[0007]

The structure of an example of the waterproof sheet of the present invention will be described with reference to FIG. The waterproof sheet of the present invention shown in FIG.
A base 1a having a fibrous base cloth 1 and waterproof layers 2 and 2'made of natural rubber, synthetic rubber or synthetic resin on both front and back surfaces thereof is provided, and the uppermost outermost layer on the waterproof layer 2 side is provided. A vinylidene fluoride resin layer 3 is formed, and between the waterproof layer 2 and the vinylidene fluoride resin layer 3, a top acrylic resin layer 4 is formed continuously with these layers. on the other hand,
On the outermost lower surface on the waterproof layer 2'side, a lower acrylic resin layer 5 is formed continuously with the waterproof layer 2 '.

In another aspect of the waterproof sheet of the present invention,
By omitting the waterproof layers 2 and 2'as described above, the upper and lower acrylic resin layers 4 and 5 can be directly formed on each of the front and back surfaces of the fibrous base fabric 1 to form the waterproof layers. Alternatively,
Any other layer may be formed between the waterproof layer 2 and the upper acrylic resin layer 4, and another arbitrary layer may be formed between the waterproof layer 2'and the lower acrylic resin layer 5. You can also Further, the waterproof layer 2'may be omitted, or the waterproof layer 2'may be omitted and other arbitrary layer may be formed instead.

That is, the essential requirements for the waterproof sheet of the present invention are that it has a fibrous base fabric as an inner layer, has a waterproof layer, and has a vinylidene fluoride resin layer as the outermost layer on the upper surface of the substrate. That is, an upper surface acrylic resin layer is continuously formed under the lower surface, and a lower surface acrylic resin layer is formed as an outermost layer on the lower surface of the substrate.

The present invention will be described in more detail below. The fibrous base fabric used in the waterproof sheet of the present invention includes natural fibers such as cotton and hemp, inorganic fibers such as glass fiber, carbon fiber and metal fiber, recycled fibers such as viscose rayon and cupra. , Semi-synthetic fiber,
For example, di- and tri-acetate fibers, and synthetic fibers such as polyamide (nylon 6, nylon 6).
6 etc.) fiber, polyester (polyethylene terephthalate etc.) fiber, aromatic polyamide fiber, acrylic fiber, polyvinyl chloride fiber, polyolefin fiber and the like.

The fibers in the base cloth may be any shape such as short fiber spun yarn, long fiber yarn, split yarn, tape yarn, etc. The base fabric may be woven fabric, knitted fabric,
It may be either a non-woven fabric or a composite fabric of these. Generally, the fibers used in the waterproof sheet of the present invention are preferably polyester fibers, which are preferably in the form of long fibers (filaments), and preferably form a plain woven fabric. Further, a woven fabric formed by stacking warp yarns and weft yarns arranged in parallel so as to intersect each other and pressing them with a twine yarn is particularly preferable. The fibrous base fabric is useful for maintaining the mechanical strength of the obtained tarpaulin at a high level.

In the present invention, a waterproof sheet is formed by forming a waterproof layer on the surface or both sides of the fibrous base fabric, and the waterproof layer is made of natural rubber, neoprene rubber, chloroprene rubber, Silicone rubber, Hypalon and other synthetic rubber, or PVC resin, ethylene-
Vinyl acetate copolymer (EVA) resin, acrylic resin,
Silicone resin, urethane resin, polyethylene (PE)
Resins, polypropylene (PP) resins, polyester resins, fluorine-containing resins and other synthetic resins can be used. The waterproof layer made of such a material has a thickness sufficient to impart desired waterproofness and flame retardancy and mechanical strength to the resulting waterproof sheet, for example, 0.05 mm or more, preferably 0.05 to. It has a thickness of 1.0 mm.

These waterproof layers are formed by a known method such as a topping, calendering, coating or dipping method using a film, solution, paste or straight film of the above rubber or resin.
It can be formed on a fibrous base fabric. These rubbers or resins may contain a plasticizer, a stabilizer, a colorant, an ultraviolet absorber, and other function-imparting agents.

As the acrylic resin which is useful in the present invention and which constitutes the lower acrylic resin layer, a polymer or copolymer mainly containing a C _{1 to} C ₄ alcohol ester of acrylic acid or methacrylic acid as a main constituent monomer is mainly used. Resin as a component is preferable. Specific examples of the main constituent monomer of such an acrylic ester resin include methyl acrylate, methyl methacrylate, ethyl acrylate,
Ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate, especially methyl acrylate and methyl methacrylate. Examples of comonomers copolymerized with these main constituent monomers include esters of C _{1 to} C ₁₂ alcohols of acrylic acid or methacrylic acid, vinyl fluoride, vinylidene fluoride, vinyl chloride, vinylidene chloride, vinyl acetate, styrene. , Acrylonitrile, methacrylonitrile and butadiene.

These copolymers are not limited to random copolymers, but may be graft copolymers. For example, a polymer obtained by adding vinylidene fluoride to a methyl methacrylate polymer and then graft-polymerizing this may be used. An acrylate containing an amino group, an imino group, an ethyleneimine residue, or an alkylenediamine residue can be used, but particularly preferable results are obtained when an acrylate containing an aziridinyl group is used.

The upper and lower acrylic resin layers may contain a small amount of another resin having good compatibility with the acrylic resin. In particular, PVC resin and vinylidene fluoride resin are
Since both have good compatibility with acrylic resin,
It is useful. Further, an ultraviolet absorber (UVA) may be blended in the upper and lower acrylic resin layers in order to provide durable weather resistance. It is preferable that the compounding amount of UVA is determined so that the incident ultraviolet light can be blocked by about 50% or more.
This UV blocking amount depends on the UVA concentration and the concentration of UVA in the lower acrylic resin layer and the thickness of this layer. If the UVA concentration is too low, the thickness of the upper and lower acrylic resin layers will increase. Need to be done, and therefore above
UVA concentration of the lower acrylic resin layer is preferably 0.3%
Above, more preferably 1.0% or more.

However, the UV in the top acrylic resin layer
If the A concentration is too high, bleeding may occur at the interface with the vinylidene fluoride resin layer forming the uppermost outer layer, and the adhesive strength with this layer may be reduced, which is not preferable. of course,
Since the compatibility of acrylic resin and vinylidene fluoride resin differs depending on the type of UVA, the upper limit of the concentration is different, but even when using benzotriazole-based UVA which has a relatively high affinity for vinylidene fluoride resin However, if the amount added exceeds 30 PHR, peeling easily occurs at the interface between both layers, so it is preferable to keep the amount below 30 PHR. As the UVA, not only benzotriazole-based UVA, but also benzophenone-based, salicylate-based UVA, or those obtained by copolymerizing these with other resins is not particularly limited. .

In the waterproof sheet according to the present invention, on the upper surface side of the substrate, on the upper surface acrylic resin layer,
A vinylidene fluoride resin layer is formed as the outermost layer. The vinylidene fluoride resin contains vinylidene fluoride in an amount of 70 mol% or more in addition to vinylidene fluoride homopolymer.
Monomer copolymerizable therewith, for example, one or more kinds selected from tetrafluoroethylene, trifluoroethylene, vinyl fluoride, trifluoroethylene chloride, fluorochlorovinylidene, vinylidene hexafluoride, etc. A copolymer obtained by copolymerizing the body is used.

In some cases, it is possible to prepare a mixture in which another resin having good compatibility with these homopolymers or copolymers is added. Examples of the resin having good compatibility with such vinylidene fluoride resin include, for example, a polymer or copolymer mainly composed of methyl methacrylate or methyl acrylate, or cyanoethylated ethylene-
Examples include vinyl alcohol copolymers. However, the content of these other resin components is preferably within 30 PHR of the constituent resin amount.

If necessary, the vinylidene fluoride resin layer may contain stabilizers, processing aids such as lubricants, and UVA. In particular, addition of UVA is preferable from the viewpoint of preventing photodegradation of the acrylic resin in the vicinity of the joint surface with the acrylic resin layer. However, the amount of UVA that is compatible with the vinylidene fluoride resin in a uniform phase is not so large, and is generally 3% or less. In addition, since the vinylidene fluoride resin layer is generally extremely thin, it cannot be expected that UVA of this layer completely protects the waterproof layer.

In the waterproof sheet of the present invention, since the vinylidene fluoride resin layer protects only the surface layer of the waterproof sheet, it preferably has a thickness of 0.3 to 10 μm, preferably 1 to 5 μm. More preferable. On the other hand, the thickness of the upper acrylic resin layer is preferably 0.5 to 30 μm,
The thickness is more preferably 2 to 20 μm, and is generally preferably larger than the thickness of the vinylidene fluoride resin layer.

In producing the waterproof sheet of the present invention, for example, a substrate having a waterproof layer formed on the front surface or both front and back surfaces of a fibrous base fabric is first produced, and then an acrylic resin and a vinylidene fluoride resin are sequentially formed on the upper surface thereof. Alternatively, a laminated film of vinylidene fluoride resin / acrylic resin, which is separately manufactured, may be attached to the surface of the substrate as another method. When the thickness of the vinylidene fluoride / acrylic resin laminated film is thin and a problem occurs in workability, the vinylidene fluoride / acrylic resin further contains a PVC film having a thickness of 30 to 50 μm as a support. It is also possible to make a laminated film made of / PVC resin and attach it to the above-mentioned substrate. The method for producing such a laminated film is not particularly limited, and for example, each layer-forming resin is compositely flowed from a composite T die or a composite cylindrical die, and a flat sheet or a cylinder is coextruded,
From the viewpoint of the adhesiveness between layers and the productivity, it is desirable to use a usual method of taking the material out and then heat treating it if necessary.

In the waterproof sheet of the present invention, the thickness and material of the lower surface acrylic resin layer forming the outermost layer on the lower surface of the substrate can be selected in substantially the same manner as described above for the upper surface acrylic resin layer. In this case, since the lower surface of the waterproof sheet is rarely exposed to direct sunlight, it is not necessary to mix UVA in the lower acrylic resin layer as much as in the upper surface, and the compounding can be omitted. Also, this layer is
The film can be formed by applying a film as described above or by coating.

The thus obtained waterproof sheet of the present invention has excellent antifouling property and weather resistance, and can be heat-sealed. That is, two sheets of this waterproof sheet are piled up,
The uppermost outermost vinylidene fluoride resin layer and the lowermost outermost lower surface acrylic resin layer are contacted with each other, and these are fusion-bonded by ultrasonic heating, high-frequency heating or hot air. When the heat-sealing is performed in this manner, the adhesive force is 0 in a waterproof sheet having no lower surface acrylic resin layer as the outermost surface of the lower surface of the base, as in the conventional waterproof sheet.
Although it was as extremely small as ~ 3 kg / 3 cm, in the case of the waterproof sheet of the present invention, the adhesive strength was 6-10 kg / 3 cm, which is a preferable value exceeding about 5 kg / 3 cm which is practically required.

Further, in the conventional waterproof sheet having no lower surface acrylic resin layer as the outermost layer on the lower surface of the substrate, it is necessary to bond an adhesive film made of a resin which gives a preferable adhesive force at the time of the above-mentioned heat-sealing. Although it may be possible to sandwich the two sheets of waterproofing sheet between them to be fusion-bonded to each other, in this case, since the adhesiveness between the front and back surfaces of the waterproofing sheet and the adhesive film is insufficient, the adhesive force between the waterproofing sheets is not sufficient. Is about 3 to 4 kg / 3 cm, and there is a difficulty in positioning a necessary portion during the fusion work, which is not preferable in terms of work. Further, it is conceivable to form a lower surface acrylic resin layer partially (discontinuously) on the lower surface side of the substrate in place of the lower surface acrylic resin continuous layer forming the outermost surface of the lower surface of the present invention. It is troublesome to apply the material to the parts that need to be joined, which lowers the workability and harms the work environment. Therefore, if the lower surface acrylic resin layer is formed as a continuous layer on the entire lower surface of the substrate from the beginning like the waterproof sheet of the present invention, the waterproof sheet itself can be manufactured inexpensively and easily, and can be sewn. Has the advantage that it can be performed on all parts of the tarpaulin.

[0026]

EXAMPLES The present invention will be further described below with reference to examples. Example 1 The following organization: A unit weight of vinylon fiber having a basis weight of 360 g / m ² was used as a base fabric, which was blanched and dried.

Next, this base cloth was made into the following composition: PVC resin ... 80 parts by weight Butylbenzyl phthalate ... 68 parts by weight Epoxidized soybean oil ... 7 parts by weight Calcium carbonate ... 20 parts by weight Cadmium barium stabilizer ... 3 parts by weight Pigment: 8 parts by weight Toluene (solvent): 130 parts by weight.
It was squeezed to 0%, dried at 90 ° C. for 1 minute, and then heat-treated at 180 ° C. for 1 minute to gel and adhere PVC to prepare a waterproof sheet substrate. The waterproof layer of the waterproof sheet substrate had a thickness of 0.3 mm.

On the upper surface of this waterproof sheet substrate, a KFC sheet (vinylidene fluoride resin (2 to 3 μm) / acrylic resin (2 to 4 μm) / PVC manufactured by Kureha Chemical Industry Co., Ltd.
Resin (45 μm)] was laminated so that its PVC surface would overlap the upper surface of the waterproof sheet substrate, and the resin (45 μm) was attached by heating.
Further, an acrylic resin film (thickness: 25 μm) manufactured by Mitsubishi Rayon Co., Ltd. was heat-bonded to the lower surface side of the waterproof sheet substrate to obtain the waterproof sheet of the present invention.

For comparison, a waterproof sheet as a conventional product was manufactured in exactly the same manner as above except that the lower surface acrylic resin film was not attached to the lower surface of the substrate.

For each of these two tarpaulin samples, the end portion 3 cm was superposed as described in the above text, and the superposed portion had an output of 2 kW and a frequency of 40.68.
High frequency treatment was performed for 3 seconds by a high frequency oscillator of MHz. In the case of the waterproof sheet of the present invention, the average peel strength of the joint portion of the heat-sealed waterproof sheet thus obtained is 8.
5kg / 3cm, and 1.5kg / 3 for the comparative waterproof sheet
It was cm. That is, the waterproof sheet of the present invention had a bonding strength sufficient for practical use, but the bonding strength of the comparative waterproof sheet was not practical.

Also, the portions to be joined of the waterproof sheet are made to face each other and overlapped, and a Leister hot air welding machine is used to obtain a width of 3 cm.
Insert a nozzle with a flat hot air outlet of No. 2 between the overlapping parts, and while moving the nozzle along the surface of the waterproof sheet in the sewing direction of the waterproof sheet, apply hot air of 400 ° C. from the nozzle to a width of about 3 cm. The resin was melted. Subsequent to this melting operation, the overlapped portion was pressed by a pressure roller and was fused and sewn. The peel strengths of the two types of fusion-sealing waterproof sheets thus obtained were exactly the same as the peel strengths of the two types of waterproof sheets obtained by the high-frequency welder sewing.

Example 2 A substrate was formed by forming a Hypalon resin waterproof layer, a silicone resin waterproof layer, an EVA resin waterproof layer and a urethane resin waterproof layer on the same base fabric as used in Example 1,
Acrylic adhesive S made by Sony Chemicals on the surface
The KFC film used in Example 1 was attached using C462. In addition, an adhesive SC462 is applied to the entire lower surface of the substrate by 5
A waterproof sheet according to the present invention was prepared by applying the resin to a thickness of μm and forming a lower acrylic resin layer. Further, as a comparative example, a waterproof sheet in which a lower acrylic layer is not formed on each of the lower surfaces of the base body was prepared as a comparative waterproof sheet.

Each of these waterproof sheets was subjected to the same high-frequency welder sewing as described in Example 1. As a result, the peel strength of the obtained sewn part was as follows. Waterproof layer Inventive sheet Comparative sheet Hypalon resin 7.5kg / 3cm 0.5kg / 3cm Silicone resin 7.0kg / 3cm 0 EVA resin 8.0kg / 3cm 1.0kg / 3cm Urethane resin 8.0kg / 3cm 1.0kg / Further, a waterproof layer was formed on both sides of the base fabric of acrylic resin to form a substrate, and a KFC sheet was attached to the upper surface of the substrate in the same manner as above, and high-frequency welder sewing was performed. The peeling strength of the obtained waterproof sheet sewn portion was 8.5 kg / 3 cm.

[0034]

As can be seen from the above, since the waterproof sheet according to the present invention has a vinylidene fluoride resin protective layer on its upper surface, it retains excellent antifouling property, weather resistance and durability. Since it has a lower surface acrylic resin layer on the entire surface on the lower surface side, it is useful as a waterproof sheet that can be easily and inexpensively sewn by high-frequency wave, ultra-short wave or heat fusion, and the industrial value of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view schematically showing an example of the waterproof sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fibrous base cloth 1a ... Base | substrate 2, 2 '... Waterproof layer 3 ... Vinylidene fluoride resin layer 4 ... Upper surface acrylic resin layer 5 ... Lower surface acrylic resin layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B29K 33:04

Claims (11)

[Claims] 1. A waterproof sheet base having a fibrous base cloth and a waterproof layer formed on the front surface or both surfaces of the base cloth and made of natural rubber, synthetic rubber or synthetic resin, and an upper surface side of the base. A vinylidene fluoride resin layer is formed as the outermost layer, and an upper surface acrylic resin layer is continuously formed under the outermost layer, and a lower surface acrylic resin layer is formed as the outermost layer on the lower surface side of the base. A waterproof sheet that can be sewn by heat fusion. 2. The waterproof sheet according to claim 1, wherein an upper surface acrylic resin layer is formed on the waterproof layer on the upper surface of the base, and a vinylidene fluoride resin layer is formed on the upper surface acrylic resin layer. 3. The waterproof sheet according to claim 1, wherein a lower surface acrylic resin layer is formed on the waterproof layer on the lower surface of the base body. 4. The waterproof sheet according to claim 1, wherein each of the upper and lower acrylic resin layers forms a waterproof layer. 5. The waterproof sheet according to claim 1, wherein the waterproof layer has a thickness of 0.05 to 1.0 mm. 6. The upper and lower acrylic resin layers,
Each C ₁ -C ₄ acrylic acid or methacrylic acid
A resin containing a polymer or copolymer containing an ester of alcohol as a main constituent monomer as a main component.
The waterproof sheet according to any one of 5 above. 7. The upper and lower acrylic resin layers,
7. Each having a thickness of 0.5 to 30 .mu.m.
The waterproof sheet according to any one of 1. 8. The waterproof sheet according to claim 7, wherein the upper and lower acrylic resin layers each have a thickness of 2 to 20 μm. 9. The vinylidene fluoride resin layer comprises a vinylidene fluoride homopolymer or a resin containing as a main component a vinylidene fluoride copolymer containing 70 mol% or more of vinylidene fluoride. The waterproof sheet according to item 1. 10. The vinylidene fluoride resin layer is 0.3.
The waterproof sheet according to claim 1, having a thickness of 10 μm. 11. The waterproof sheet according to claim 10, wherein the vinylidene fluoride resin layer has a thickness of 1 to 5 μm.